Base44 Coder

Build apps on the Base44 platform using the Base44 JavaScript SDK.

⚡ IMMEDIATE ACTION REQUIRED - Read This First

This skill activates on ANY mention of "base44" or when a base44/ folder exists. DO NOT read documentation files or search the web before acting.

Your first action MUST be:

1. Check if base44/config.jsonc exists in the current directory
2. If YES (existing project scenario):
   • This skill (base44-sdk) handles the request
   • Implement features using Base44 SDK
   • Do NOT use base44-cli unless user explicitly requests CLI commands
3. If NO (new project scenario):
   • Transfer to base44-cli skill for project initialization
   • This skill cannot help until project is initialized

When to Use This Skill vs base44-cli

Use base44-sdk when:

• Building features in an EXISTING Base44 project
• base44/config.jsonc already exists in the project
• Base44 SDK imports are present (@base44/sdk)
• Writing JavaScript/TypeScript code using Base44 SDK modules
• Implementing functionality, components, or features
• User mentions: "implement", "build a feature", "add functionality", "write code for"
• User says "create a [type] app" and a Base44 project already exists

DO NOT USE base44-sdk for:

• ❌ Initializing new Base44 projects (use base44-cli instead)
• ❌ Empty directories without Base44 configuration
• ❌ When user says "create a new Base44 project/app/site" and no project exists
• ❌ CLI commands like npx base44 create, npx base44 deploy, npx base44 login (use base44-cli)

Skill Dependencies:

• base44-sdk assumes a Base44 project is already initialized
• base44-cli is a prerequisite for base44-sdk in new projects
• If user wants to "create an app" and no Base44 project exists, use base44-cli first

State Check Logic: Before selecting this skill, verify:

• IF (user mentions "create/build app" OR "make a project"):
  • IF (directory is empty OR no base44/config.jsonc exists): → Use base44-cli (project initialization needed)
  • ELSE: → Use base44-sdk (project exists, build features)

Quick Start

// In Base44-generated apps, base44 client is pre-configured and available

// CRUD operations
const task = await base44.entities.Task.create({ title: "New task", status: "pending" });
const tasks = await base44.entities.Task.list();
await base44.entities.Task.update(task.id, { status: "done" });

// Get current user
const user = await base44.auth.me();

// External apps
import { createClient } from "@base44/sdk";

// IMPORTANT: Use 'appId' (NOT 'clientId' or 'id')
const base44 = createClient({ appId: "your-app-id" });
await base44.auth.loginViaEmailPassword("user@example.com", "password");

⚠️ CRITICAL: Do Not Hallucinate APIs

Before writing ANY Base44 code, verify method names against this table or QUICK_REFERENCE.md.

Base44 SDK has unique method names. Do NOT assume patterns from Firebase, Supabase, or other SDKs.

Authentication - WRONG vs CORRECT

Functions - WRONG vs CORRECT

Integrations - WRONG vs CORRECT

Entities - WRONG vs CORRECT

SDK Modules

For client setup and authentication modes, see client.md.

TypeScript and type registries

Each reference file includes a "Type Definitions" section with TypeScript interfaces and types for the module's methods, parameters, and return values.

Getting typed entities, functions, and agents: The Base44 CLI generates types from your project resources (entities, functions, agents), including augmentations to EntityTypeRegistry, FunctionNameRegistry, and AgentNameRegistry, and wires them into your project so you get autocomplete and type checking without manual setup. For how to generate types, use the base44-cli skill.

Manual augmentation: You can instead augment the registries yourself in a .d.ts file; see the Type Definitions sections in entities.md, functions.md, and base44-agents.md.

Installation

Install the Base44 SDK:

npm install @base44/sdk

Important: Never assume or hardcode the @base44/sdk package version. Always install without a version specifier to get the latest version.

Creating a Client (External Apps)

When creating a client in external apps, ALWAYS use appId as the parameter name:

import { createClient } from "@base44/sdk";

// ✅ CORRECT
const base44 = createClient({ appId: "your-app-id" });

// ❌ WRONG - Do NOT use these:
// const base44 = createClient({ clientId: "your-app-id" });  // WRONG
// const base44 = createClient({ id: "your-app-id" });        // WRONG

Required parameter: appId (string) - Your Base44 application ID

Optional parameters:

• token (string) - Pre-authenticated user token
• options (object) - Configuration options
  • options.onError (function) - Global error handler

Example with error handler:

const base44 = createClient({
  appId: "your-app-id",
  options: {
    onError: (error) => {
      console.error("Base44 error:", error);
    }
  }
});

Module Selection

Working with app data?

• Create/read/update/delete records → entities
• Import data from file → entities.importEntities()
• Realtime updates → entities.EntityName.subscribe()

User management?

• Login/register/logout → auth
• Get current user → auth.me()
• Update user profile → auth.updateMe()
• Invite users → users.inviteUser()

AI features?

• Chat with AI agents → agents (requires logged-in user)
• Create new conversation → agents.createConversation()
• Manage conversations → agents.getConversations()
• Generate text/JSON with AI → integrations.Core.InvokeLLM()
• Generate images → integrations.Core.GenerateImage()

Custom backend logic?

• Run server-side code → functions.invoke()
• Need admin access → base44.asServiceRole.functions.invoke()

External services?

• Send emails → integrations.Core.SendEmail()
• Upload files → integrations.Core.UploadFile()
• Custom APIs → integrations.custom.call()
• OAuth tokens (Google, Slack) → connectors (backend only)

Tracking and analytics?

• Track custom events → analytics.track()
• Log page views/activity → appLogs.logUserInApp()

Common Patterns

Filter and Sort Data

const pendingTasks = await base44.entities.Task.filter(
  { status: "pending", assignedTo: userId },  // query
  "-created_date",                             // sort (descending)
  10,                                          // limit
  0                                            // skip
);

Protected Routes (check auth)

const user = await base44.auth.me();
if (!user) {
  // Navigate to your custom login page
  navigate('/login', { state: { returnTo: window.location.pathname } });
  return;
}

Backend Function Call

// Frontend
const result = await base44.functions.invoke("processOrder", {
  orderId: "123",
  action: "ship"
});

// Backend function (Deno)
import { createClientFromRequest } from "npm:@base44/sdk";

Deno.serve(async (req) => {
  const base44 = createClientFromRequest(req);
  const { orderId, action } = await req.json();
  // Process with service role for admin access
  const order = await base44.asServiceRole.entities.Orders.get(orderId);
  return Response.json({ success: true });
});

Service Role Access

Use asServiceRole in backend functions for admin-level operations:

// User mode - respects permissions
const myTasks = await base44.entities.Task.list();

// Service role - full access (backend only)
const allTasks = await base44.asServiceRole.entities.Task.list();
const token = await base44.asServiceRole.connectors.getAccessToken("slack");

Frontend vs Backend

Backend functions use Deno.serve() and createClientFromRequest(req) to get a properly authenticated client.